1. Field of the Invention
This invention relates to adjustable gas cylinder controls and particularly to adjustable chair controls.
2. Description of the Piror Art
The use of a gas-operated cylinder and piston combination is well known in the art. Also known is the use of such a combination in connection with a chair base and seat and the use of means for adjusting the overall length of the combination thereby adjusting the height of the chair seat. The following is a list of relevant patents in this regard:
______________________________________ Pat. No. Issue Date Inventor ______________________________________ 3,656,593 4/18/72 Bauer 3,756,654 9/04/73 Bauer 3,711,054 1/16/73 Bauer 3,790,119 2/05/74 Bauer 3,837,704 9/24/74 Bauer 3,762,514 10/02/73 Freitag 3,787,019 1/22/74 Freitag 3,828,651 8/13/74 Dorner et al. 3,788,587 1/29/74 Stemmler 3,388,883 6/18/68 Axthammer et al. 3,760,911 9/25/73 Porter et al. 3,744,844 7/10/73 Nomaki et al. 3,739,885 6/19/73 Bainbridge 3,712,429 1/23/73 Otto 3,628,637 12/21/71 Axthammer 3,407,909 10/29/68 Seckerson et al. 3,326,604 6/20/67 Billingham et al. 3,528,532 9/15/70 Moskow 3,533,658 10/13/70 Gropp 3,765,720 10/16/73 Sakai ______________________________________
However varied the cylinder and piston designs in the above references, several general characterizations can be made. First, the majority of designs are intricate and complex arrangements. Several involve more than one cylinder chamber or bore while others divide a single cylinder bore into more than two separate compartments using a variety of walls and partitions. The adjustable controls in such references are also generally intricate arrangements involving the combination of various pins, valves, members, discs, seals and springs. The manufacture of these intricate cylinder and piston arrangements is often detailed and very costly both in terms of time and production expenditures.
Second, as to the prior art cylinder controls specifically adapted for use in a chair, such controls generally require additional structure such as a guide tube in order to adequately support the chair seat and individual, as shown in Stemmler, Bauer U.S. Pat. No. 3,790,119, Bauer U.S. Pat. No. 3,711,054, Bauer U.S. Pat. No. 3,837,704, and Bauer U.S. Pat. No. 3,756,654. Furthermore, the handle or lever provided for adjusting the height of such controls is generally mounted within the housing on the underside of the chair seat thereby complicating removal and preventing the control from being readily interchangeable with various other chair seats and bases.
The present invention alleviates the above disadvantages. A single tube and single piston arrangement is provided wherein construction and manufacture is very simple. The valve means and lever means provided for allowing gas flow between the two compartments in the tube avoid the complexities of the prior art while providing a ready means of adjusting the height of the control. The adjustable chair control comprising the preferred embodiment of the present invention further resolves the problems of prior art controls by providing a structurally sound support which is adapted to fit a variety of chair seats and bases.